1. Field of the Invention
The present invention relates, in general, to valves, and in particular, to seats and seals for high pressure valves.
2. Information Disclosure Statement
It is often desired to have a valve for selectively gating liquid from an input port to an output port. Well-known representative solutions for this problem include so-called “knife gate” valves, ball valves, and butterfly valves. With all of these valves, a valve member moves within a valve body, and a seal is interposed between the valve body and the moving valve member. As the valve member moves from an “open” or first position to a “closed” or second position, whether a reciprocating gate, a ball that rotates about an axis, or butterfly flaps or wings that move angularly about an axis, communication between a first port of the valve is selectively opened or closed, as desired.
Furthermore, the pressure rating of the valve is directly affected by the effectiveness of the valve seal that is interposed between the valve body and the valve member, and friction between the valve seal and the moving valve member determines the force required to move the valve member between open and closed positions. Typically, for valves capable of operating under extremely high-pressure, movement of the valve member between open and closed positions is not a frequent event, but, when closed, the valve must withstand extreme pressure at the input port.
A major expense for such valves is the well-known actuator, whether a hydraulic or pneumatic cylinder, or a manually-actuated wheel or lever, or an electric motor actuator, each of which causes the valve member to move between the open and closed positions. As the force necessary for moving the valve member increases, as happens in the prior art as the size (rated flow and rated pressure) of the valve increases, a more powerful actuator is required to move the valve member.
A prior art attempt to solve this problem and to reduce the actuation force required is that offered by the Roto-Disc Company, 50 W. Tecnecenter Drive, Suite B-2, Milford, Ohio 45150, which sells a series of inflatable-seal spherical valves under the trademark Roto-Flate. These valves have an inflatable valve seal that is deflated while the valve member is moving from open to closed positions, and, when the valve member is in the closed position, an external air source inflates the valve seal to cause tight sealing between the valve body and the valve member. Such an approach has the disadvantage of requiring an external air source to inflate the valve seal, together with a control mechanism to inflate and deflate the seal as required. Even so, such a valve with an inflatable seal has a rather low pressure rating on the order of 150 psig (pound-force per square inch gauge).
It is thus desirable to have a valve seal for a valve that can withstand high pressure and which seals the valve member to the valve body without requiring inflation while, at the same time, permits lower-force actuators than heretofore required by such valves.